Bluebloods

What color is blood that is running through our veins? Why does it look blue under our skin? Why is it red when it comes out and not blue? Answer settles a respectable bet.

-- Bbygirl & Daddee, the net

Awwww, how cutesie-wootsie-icky-ookie. Love sometimes makes you wanna throw up. But say, snugglebunnies, we'd all love to know how you got from, "No, I love you more!" "No, I love you more!""Nooooo, I love you more?" to, "Gee, why is there red blood running off my big I-love-you-more head?" Somebody whap somebody else with a lamp? Must have been some sort of bet, I'll say. If you promise to stop smooching on the couch for a minute, we'll clear up the question.

Unless you're a clam or certain bugs, your blood is red. Bright red or a dark, brownish red. Blood is not blue. But then neither is a bluebird or the sky. They're all just tricks of light. And a couple of scientists got so tired of being asked this question at cocktail parties, they finally analyzed it. Bright red blood in our arteries is full of oxygen. Once blood has made a circuit through the body and is heading back to our heart and lungs for a new charge, the oxygen is depleted, and it's turned a sludgy color. That's the stuff that looks blue through fair skin. When light hits skin, it can penetrate about .08 of an inch. If there's a vein in that area, the blood absorbs the red end of the spectrum, so what we see from the outside are the remaining blue wavelengths coming back through a particular thickness of fair skin.

But, hey, Matt, you say, when snookie-ookums gives me a big kiss and I blush, my cheeks don't turn blue, they turn red. So whadda ya say about that one, huh? Well, I say, the red of a blush is from blood in capillaries very close to the skin's surface. The blue trick works only if the blood source is at least .02 of an inch below the skin. So now you two thank the scientists for the answer and hit the love trail outta here.